This invention relates generally to visibility of aircraft, and more particularly, to methods and systems for improving aircraft visibility by addressing aircraft visibility issues associated with aircraft on the ground.
Current collision avoidance techniques are designed for use primarily while an airplane is in flight, with ground and air traffic control being responsible for safely authorizing ground transit, landing and departure of airplanes. One practice that pilots and air traffic control employ to ensure proper separation distances and safe aircraft operation is the principal of “See and Avoid”. The aircraft's paint scheme and exterior lighting systems play a large role in this practice. To enhance their conspicuity, pilots are advised to turn on all exterior lights when operating below a prescribed altitude. Certain aircraft exterior lights, such as the position and anticollision lights, are turned on at all times during operation day or night, unless they are bothersome to the pilot. These lights increase the conspicuity of an aircraft and provide a visual indication of an aircraft's position and direction of travel to other pilots.
While an aircraft is on the ground, anticollision and position lights can be difficult to distinguish and can blend in with other lights such as runway lights and approach lights. Aircraft are also equipped with lighting systems such as landing, taxi, and runway turnoff lights which serve to illuminate the ground during ground operations, takeoff/departure, and approach/landing. These lights can also increase an aircraft's conspicuity in certain situations. The landing lights however, are very intense and are generally used only during the approach/landing and takeoff/departure phases of flight. While an aircraft is maneuvered on the ground the landing lights are generally not used because they can temporarily blind other pilots and ground personnel. In other words, these lights are bothersome to those operating aircraft and other ground vehicles in the vicinity of an aircraft using such lights, and their use may actually create unsafe situations in certain situations. The intensity of these lights in a ground operations environment is hazardous in one regard, as the beam is certainly blinding to operators of equipment in the vicinity.
An aircraft's paint scheme can also effect its conspicuity. In order for an object to be visible, there must be some contrast with its surroundings. Dark colors when viewed against a dark background, or colors which blend in with surroundings can make an aircraft difficult to see in certain situations.
There are instances when an aircraft is difficult to discern in a dark environment. Existing aircraft exterior lights such as position lights and anticollision lights can often blend in with surroundings when many light sources, such as runway or approach lights, are present in the background. Also, it is often difficult to judge the distance to a single light source if the source itself is very small. Conversely, sources of light which are large can often enable a pilot to judge the distance and orientation. For example, logo lights that illuminate the vertical stabilizer of an aircraft, can improve a pilot's ability to more effectively judge the orientation and distance to the illuminated aircraft from certain directions. Sources of illumination such as landing, taxi, runway turnoff and logo lights can also help improve the conspicuity of an aircraft in some instances by illuminating large areas on the ground.
In spite of emphasizing the use of exterior lights to enhance the “See and Avoid” or “See and be Seen” principal, near misses or potential for ground incursions continue to be a major safety problem. There have been many instances according to aviation regulatory officials. These incidents include recent close calls and accidents that have highlighted a need for improved safety features on airplanes to supplement other methods when aircraft are maneuvering on runways and taxiways. These types of accidents have proven to be particularly devastating and are far more likely to happen than mid air collisions.
In one currently implemented configuration, a lighting system is employed that illuminates the ground underneath an aircraft, thereby creating an illuminated silhouette of the airplane visible to other aircraft that might be approaching from above it. While effective in this situation, such a system requires the addition of lights, light housings, and wiring. Such additions add weight to the aircraft while also increasing the electrical power consumption of the aircraft.
In another implemented configuration, large self illuminated or luminescent area sources called formation lights are installed on fighter aircraft and helicopters to help pilots judge their position relative to other aircraft flying in close formation. By observing the size and shape of the formation lights, military pilots can rapidly and efficiently determine the speed, orientation and distance of other aircraft with just a glance in low lighting conditions. Formation lights produce light which is more uniform and less irritating to a dark adapted pilot, compared with position lights or anticollision lights.
In some instances, anticollision lights and position lights are turned off when aircraft are flying in formation in order to prevent such irritation. Since the aircraft could have the short wingspan of a fighter jet or the large wingspan of a cargo airplane, it is very disorienting trying to determine distance and orientation using only traditional aircraft exterior lights. Formation lights are much more effective because they are area sources of light rather than point sources, allowing pilots to judge the orientation and distance of other aircraft by viewing the projected size and shape of the formation light panel. However, addition of formation lights increase the weight of an aircraft and increase the amount of electrical an aircraft must generate.
Other existing aircraft lighting and traffic avoidance systems are not specifically designed to protect against such a situation. Existing traffic avoidance lighting systems are specifically made to warn away other aircraft at greater distances and when in flight. The large variation of aircraft sizes and light installations therefore makes these systems less effective when the aircraft is on the ground and being viewed in poor lighting conditions. Additionally the position lights and anticollision lights tend to blend in with surroundings when viewed against a background that contains many other light sources This is especially common on the ground where runway lights and approach lights can make it difficult to distinguish the lights mounted on an aircraft. Air traffic and ground control are effective in most instances at maintaining safe aircraft separation, but due to human error accidents still happen. Recently the incidence of near misses at airports has been studied and has been reported to be alarmingly high. Reconstruction of recorded position data for the aircraft involved in one of these near misses has indicated that a catastrophic crash was avoided with less than 50 feet of separation.